1. Field of the Invention
The present invention relates to a coloring method which comprises coating the surface of inorganic substrates, for example, inorganic beads such as glass beads, inorganic fibers such as glass fibers, rock wool and mineral wool, mineral fiber boards and cloths obtained from the fibers, concrete molded materials such as concrete bricks and concrete electric poles, inorganic pigments such as titanium dioxide, calcium carbonate and alumina white, and metallic powders such as aluminum powder, with pigments or dyestuffs using water-soluble cationic resins.
2. Description of the Prior Art
Various methods for coloring inorganic substrates, particularly glass fibers, have been proposed, for example a dyeing with dyestuffs or pigments on the fibers previously surface-treated with silane compounds as disclosed in British Pat. No. 1,035,778, chromium compounds or other metallic ions as disclosed in Japanese Patent Publication No. 49471/72, a coating on the glass fiber cloths with pigments incorporated in resinous binders, and a transfer printing on the cloths as disclosed in Japanese Patent Publication No. 23684/72. In addition, a method which comprises making hard boards from rock wool using a binder composition containing colorants as disclosed in Japanese Patent Publication No. 5387/61 has been proposed.
These methods, however, are very disadvantageous because they are complicated to carry out and it is difficult to obtain a brilliant shade. Furthermore, coloring of inorganic pigments and aluminum powders has been described only to a small extent in the technical and patent literature.